Isolated benign primary cutaneous plasmacytosis in children: two illustrative cases.

BACKGROUND: Plasma cells are normally found in bone marrow and the intestinal tract. They appear in the skin in malignant conditions, autoimmune diseases, infection, and idiopathic and poorly understood disorders such as primary nodular amyloidosis. It is uncommon to find collections of plasma cells in the skin in the absence of these conditions. OBSERVATIONS: We present 2 cases of cutaneous plasmacytosis, one in a white, female adolescent aged 15 years with an 11-year history of a solitary, asymptomatic, violaceous plaque on the left anterior tibia and the other in a white, male child aged 7 years with a 2-year history of a solitary erythematous plaque on the right anterior tibia. In both patients, infiltration of mature polyclonal plasma cells was confined to an area on the skin with papulonodules. There was no history of previous trauma, malignant conditions, autoimmune disease, or infection in either child. CONCLUSION: Although incipient or occult systemic disease cannot be definitively ruled out, the course of these 2 individuals suggests that isolated primary cutaneous plasmacytosis in children is a benign chronic process with no adverse sequelae.

The evolving roles of alternative splicing.

Alternative splicing is now commonly thought to affect more than half of all human genes. Recent studies have investigated not only the scope but also the biological impact of alternative splicing on a large scale, revealing that its role in generating proteome diversity may be augmented by a role in regulation. For instance, protein function can be regulated by the removal of interaction or localization domains by alternative splicing. Alternative splicing can also regulate gene expression by splicing transcripts into unproductive mRNAs targeted for degradation. To fully understand the scope of alternative splicing, we must also determine how many of the predicted splice variants represent functional forms. Comparisons of alternative splicing between human and mouse genes show that predominant splice variants are usually conserved, but rare variants are less commonly shared. Evolutionary conservation of splicing patterns suggests functional importance and provides insight into the evolutionary history of alternative splicing.